Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
       3             :  *
       4             :  *  Use of this source code is governed by a BSD-style license
       5             :  *  that can be found in the LICENSE file in the root of the source
       6             :  *  tree. An additional intellectual property rights grant can be found
       7             :  *  in the file PATENTS.  All contributing project authors may
       8             :  *  be found in the AUTHORS file in the root of the source tree.
       9             :  */
      10             : 
      11             : #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/sli.h"
      12             : 
      13             : #include "webrtc/base/checks.h"
      14             : #include "webrtc/base/logging.h"
      15             : #include "webrtc/modules/rtp_rtcp/source/byte_io.h"
      16             : #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/common_header.h"
      17             : 
      18             : namespace webrtc {
      19             : namespace rtcp {
      20             : constexpr uint8_t Sli::kFeedbackMessageType;
      21             : // RFC 4585: Feedback format.
      22             : //
      23             : // Common packet format:
      24             : //
      25             : //   0                   1                   2                   3
      26             : //   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      27             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      28             : //  |V=2|P|   FMT   |       PT      |          length               |
      29             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      30             : //  |                  SSRC of packet sender                        |
      31             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      32             : //  |                  SSRC of media source                         |
      33             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      34             : //  :            Feedback Control Information (FCI)                 :
      35             : //  :                                                               :
      36             : //
      37             : // Slice loss indication (SLI) (RFC 4585).
      38             : // FCI:
      39             : //   0                   1                   2                   3
      40             : //   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      41             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      42             : //  |            First        |        Number           | PictureID |
      43             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      44           0 : Sli::Macroblocks::Macroblocks(uint8_t picture_id,
      45             :                               uint16_t first,
      46           0 :                               uint16_t number) {
      47           0 :   RTC_DCHECK_LE(first, 0x1fff);
      48           0 :   RTC_DCHECK_LE(number, 0x1fff);
      49           0 :   RTC_DCHECK_LE(picture_id, 0x3f);
      50           0 :   item_ = (first << 19) | (number << 6) | picture_id;
      51           0 : }
      52             : 
      53           0 : void Sli::Macroblocks::Parse(const uint8_t* buffer) {
      54           0 :   item_ = ByteReader<uint32_t>::ReadBigEndian(buffer);
      55           0 : }
      56             : 
      57           0 : void Sli::Macroblocks::Create(uint8_t* buffer) const {
      58           0 :   ByteWriter<uint32_t>::WriteBigEndian(buffer, item_);
      59           0 : }
      60             : 
      61           0 : bool Sli::Parse(const CommonHeader& packet) {
      62           0 :   RTC_DCHECK_EQ(packet.type(), kPacketType);
      63           0 :   RTC_DCHECK_EQ(packet.fmt(), kFeedbackMessageType);
      64             : 
      65           0 :   if (packet.payload_size_bytes() <
      66             :       kCommonFeedbackLength + Macroblocks::kLength) {
      67           0 :     LOG(LS_WARNING) << "Packet is too small to be a valid SLI packet";
      68           0 :     return false;
      69             :   }
      70             : 
      71             :   size_t number_of_items =
      72           0 :       (packet.payload_size_bytes() - kCommonFeedbackLength) /
      73           0 :       Macroblocks::kLength;
      74             : 
      75           0 :   ParseCommonFeedback(packet.payload());
      76           0 :   items_.resize(number_of_items);
      77             : 
      78           0 :   const uint8_t* next_item = packet.payload() + kCommonFeedbackLength;
      79           0 :   for (Macroblocks& item : items_) {
      80           0 :     item.Parse(next_item);
      81           0 :     next_item += Macroblocks::kLength;
      82             :   }
      83             : 
      84           0 :   return true;
      85             : }
      86             : 
      87           0 : bool Sli::Create(uint8_t* packet,
      88             :                  size_t* index,
      89             :                  size_t max_length,
      90             :                  RtcpPacket::PacketReadyCallback* callback) const {
      91           0 :   RTC_DCHECK(!items_.empty());
      92           0 :   while (*index + BlockLength() > max_length) {
      93           0 :     if (!OnBufferFull(packet, index, callback))
      94           0 :       return false;
      95             :   }
      96           0 :   CreateHeader(kFeedbackMessageType, kPacketType, HeaderLength(), packet,
      97           0 :                index);
      98           0 :   CreateCommonFeedback(packet + *index);
      99           0 :   *index += kCommonFeedbackLength;
     100           0 :   for (const Macroblocks& item : items_) {
     101           0 :     item.Create(packet + *index);
     102           0 :     *index += Macroblocks::kLength;
     103             :   }
     104           0 :   return true;
     105             : }
     106             : 
     107             : }  // namespace rtcp
     108             : }  // namespace webrtc